Arroyo noted that keeping a column still at equilibrium for 1-2hrs increases ester counts. Forgive me if I've missed it but I haven't seen much discussion on why that would be the case.
My suspicion is that esters aren't being formed in the column as one might assume. Organic acids have higher boiling points than water so they shouldn't be found in large qualities in a column at equilibrium. So what is happening? Recall the reaction for Fischer Esterification:
Alc+Acid <-> Ester+Water
Remember this reaction is reversible. Even if the products and reactants are at equilibrium and there's no net change in their concentration, esters are still constantly breaking and reforming on an individual molecular level. So really you have two reactions going on at the same time:
Alc+Acid -> Ester+Water
Ester+Water -> Alc+Acid
Ester formation can't be reversed without water!
So my hypothesis is this: Esters are forming in the boiler as normal, but instead of sticking around in the (very wet) wash where they can revert back to precursors, they're zooming up into the column and largely staying there, where they are "preserved" by the lack of H2O.
A Possible Explanation for Column Esterification
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